I have this scrollable text where the user is able to scroll so that my name is shown. I want to stop the text from being scrolled any further when the element reaches the middle of the user's screen. Is there any way to do that? Attached below is a snippet of the code.
let text = document.getElementById('text');
var textRect = text.getBoundingClientRect();
var bodyRect = document.body.getBoundingClientRect();
var w = window.innerWidth;
const scaler = 1/25
window.addEventListener('scroll', function(){
let value = window.scrollY;
if (value < w/2.65) /*when text is right of center*/{
text.style.marginRight = value * 3*scaler+ 'vw';
}
})
I have made many futile attempts at solving this issue but all have gone in vain. Thank you to anyone that helps me solve this issue.
I have tried using innerwidth to compare my value to the width of the screen and used document.body.getBoundingClientRect() but none of those have worked either
Related
I have a very long div (height: 500px), and I want to detect if user scrolled to the bottom of this div.
I have seen so many answers in the stackoverflow, almost all the answers mentioned scrollTop. However, in my simple example (jsfiddle), the scrollTop is always 0. After reading the MDN, I realize maybe they are talking about scrollable div? But all I want is to detect whether user scrolled to the bottom of a normal div.
Code
<html>
<body>
<!-- This is the very very long div, which may be contained in some other divs -->
<div></div>
</body>
</html>
jQuery Code
Currently, there is no scrollBottom function of jQuery. But, I have created a function that will tell whether we can see the bottom of a specific div element or not.
let aDiv = document.getElementById("aDiv");
$(document).scroll(function () {
var y = $(this).scrollTop();
var windowHeight = $(window).height();
var bottomVal = aDiv.offsetTop + aDiv.offsetHeight- windowHeight;
let s = document.getElementById("txt");
if(y>bottomVal && y< bottomVal + windowHeight){ s.innerHTML = "You can see bottom of aDiv";}
else{ s.innerHTML = "Can't see bottom of aDiv"; }
});
You can go through the following example. This might help you.
https://jsfiddle.net/q2smtvya/3/
Update: Added Vanilla JS Code. The only change will be the following JS Code
let aDiv = document.getElementById("aDiv");
window.onscroll = function(){
var y = window.scrollY;
var windowHeight = window.innerHeight;
var bottomVal = aDiv.offsetTop + aDiv.offsetHeight- windowHeight;
let s = document.getElementById("txt");
if(y>bottomVal && y< bottomVal + windowHeight){ s.innerHTML = "You can see bottom of aDiv";}
else{ s.innerHTML = "Can't see bottom of aDiv"; }
};
You can go through the following example. This might help you.
https://jsfiddle.net/nrp7x61k/1/
So I have a script that adds a slight shadow to table edge where you can scroll, depending on the location of the scrollbar, but it sometimes doesn't work.
This is one part of it:
$('table').on('scrollstart scrollstop', function(){
if($(this).parent().hasClass('table-wrap')){
var elem = $(this),
elemBody = elem.find('tbody'),
elemParent = elem.parent('.table-wrap');
var scrolled = (elemBody.outerWidth() - elemParent.outerWidth() - elem.scrollLeft());
if(scrolled === 0){
elemParent.addClass('left_active');
elemParent.removeClass('right_active');
} else if(elem.scrollLeft() === 0) {
elemParent.removeClass('left_active');
elemParent.addClass('right_active');
} else {
elemParent.addClass('left_active');
elemParent.addClass('right_active');
}
}
});
This part sometimes I have to add "+1" to "elem.scrollLeft() --here---); to make it work.
var scrolled = (elemBody.outerWidth() - elemParent.outerWidth() -
elem.scrollLeft());
But then I noticed, some tables it helps and on others, it stops working. Meaning when I scroll to right the 'right_active' class will not disappear.
Any suggestions?
Have you tried including scrollbar width in your calculation for var scrolled?
var scrolled = (elemBody.outerWidth() - elemParent.outerWidth() - elem.scrollLeft());
I think you are on the right track but the width is probably not precise since .outerWidth() doesn't include scrollbar width. Hence, the maximum scroll width is always greater than the actual element width.
The code:
http://codepen.io/anon/pen/EjrpMM
So, i'm working on an interesting problem. I am working with a 2000px HTML document, that has a modal placed ontop of it.
The width of the div lightbox is 80%, and it's sitting positioned fixed.
The goal is, when scrolling down the page, to control the width of the div based on the scroll position. At the bottom of the page, it's only a third in size.
I've had trouble figuring out the proper equation or formula for this, and was seeking help.
Currently, I've been trying to look at the window.pageYOffset, to add 2.5% to the div while increasing, and minus 2.5% when scrolling back up, to bring it back to it's 80% width.
However, something isn't working right. I was seeing if the community had any ideas to help solve the problem.
I'm not using any frameworks for this.
Here's my javascript:
var lightBox = document.getElementById('lightBox'),
count = 80,
num = window.pageYOffset;
document.addEventListener('scroll', function(e) {
var offset = window.pageYOffset;
num >= offset ? count += 2.5 : count -= 2.5;
num = offset;
lightBox.style.width = count + '%';
});
View the code here, in this codepen
http://codepen.io/anon/pen/EjrpMM
Thank you!
You just have to change
+= 2.5 and -=2.5 to += 0.7 and -= 0.7
When I checked your code I did this and it worked.
Scroll event fired once on scroll independently on how much you've scrolled. E.g. if you've scrolled 1px scrollbar, or scrolled 100px using mousewheel scroll event will be fired once.
So if you need stable results you will need to calculate your div width depending on scroll position (window.pageYOffset).
Check this codepen fork. I've assumed that in the end of page div width should be 50%.
Core part is:
var lightBox = document.getElementById('lightBox');
var upperBound = 80;
var lowerBound = 50;
var tickValue = (upperBound - lowerBound) / window.innerHeight;
document.addEventListener('scroll', function(e) {
var offset = window.pageYOffset;
var count = upperBound - offset * tickValue;
lightBox.style.width = count + '%';
});
Important note: for crossbrowser way to get innerHeight you can check this answer
This is a simple equation. Let f : scroll |-> f(scroll) be the function that gives you the width of your div. You want f(0) = 0.8, f(2000)= 1/3.
Let's say you want the progression to be linear so f(scroll) = a*scroll + b, you can easily deduce that b = 0.8 and a = (1/3 - 0.8)/2000 = -0.000233. Now for any scroll value, you can find the width of your div.
Now you can change the values when you want, f(scroll) = (minWidth-maxWidth)/pageLength * scroll + maxWidth.
Here is a link to a JSFiddle http://jsfiddle.net/9NYcn/11/ i put together with what i would like to do, but i need to do this with pure css.
function expand(){
var sect = document.getElementById("sect");
var body = document.getElementById("main");
var panes = document.getElementById("panes");
var newHeight = 40 + "px";
var newHeight2 = 120 + "px";
var topVal = 120 + "px";
sect.style.display = "block";
sect.style.height = newHeight;
body.style.height = newHeight2;
panes.style.top = topVal;
}
In the above function i had to set the "top" property of panes in order to get this to work. i need to get it so that the panes section will work like it currently does without using javascript to change the "top" property of "panes". When the user clicks the "expand" button the div with the class "body" will expand and not stick behind or overlap the "panes" div.
I know im doing a terrible job explaining i apologize for that.
Remove the absolute positioning of .panes: http://jsfiddle.net/rHTM8/
It will make it naturally flow after the middle div.
I am having this problem where i have a set of 6 UL's having a common class x.Each of them consist of a specific section of the page.Now i have 6 menus that are related to each of the section.What i have to do is highlight the menu when its related section is in users view.
For this i thought that may be jQuery position(); or offset(); could have helped but they give the top and left of the element.I also tried using jQuery viewport plugin but apparently view port is big it can show more than one UL at a time hence i cant apply element specific logic here.I am not familliar to this but does anything changes of an element on scrolling?If yes then how to access it?
Please share your views.
Regards
Himanshu Sharma.
Is very easy to do it using jQuery and a dummy fixed HTML block that helps you find the current position of the viewport.
$(window).on("scroll load",function(){
var once = true;
$(".title").each(function(ele, index){
if($(this).offset().top > $("#viewport_helper").offset().top && once){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
once = false;
}
});
})
Check out a working example: http://jsfiddle.net/6c8Az/1/
You could also do something similar with the jQuery plugin, together with the :first selector:
$(window).on("scroll load",function(){
$(".title:in-viewport:first").each(function(){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
});
})
You can get the viewport's width and height via $(document).width() and $(document).height()
You can get how many pixels user scrolls via $(document).scrollTop() and $(document).scrollLeft
Combining 1 and 2, you can calculate where the viewport rectangle is
You can get the rectangle of an element using $(element).offset(), $(element).width() and $(element).height()
So the only thing left to you is to determine whether the viewport's rectangle contains (or interacts) the elements's rectangle
So the whole code may look like:
/**
* Check wether outer contains inner
* You can change this logic to matches what you need
*/
function rectContains(outer, inner) {
return outer.top <= inner.top &&
outer.bottom >= inner.bottom &&
outer.left <= inner.left &&
outer.right >= inner.right;
}
/**
* Use this function to find the menu related to <ul> element
*/
function findRelatedMenu(element) {
return $('#menu-' + element.attr('id'));
}
function whenScroll() {
var doc = $(document);
var elem = $(element);
var viewportRect = {
top: doc.scrollTop(),
left: doc.scrollLeft(),
width: doc.width(),
height: doc.height()
};
viewportRect.bottom = viewportRect.top + viewportRect.height;
viewportRect.right = viewportRect.left + viewportRect.width;
var elements = $('ul.your-class');
for (var i = 0; i < elements.length; i++) {
var elem = $(elements[i]);
var elementRect = {
top: elem.offset().top,
left: elem.offset().left,
width: elem.width(),
height: elem.height()
};
elementRect.bottom = elementRect.top + elementRect.height;
elementRect.right = elementRect.left + elementRect.width;
if (rectContains(viewportRect, elementRect)) {
findRelatedMenu(elem).addClass('highlight');
}
}
}
$(window).on('scroll', whenScroll);
Let's see if i understood well. You have a page long enough to scroll, and there is an element that when it appears in the viewport, you wanna do something with it. So the only event that's is triggered for sure on the time the element gets in the viewport is the 'scroll'. So if the element is on the page and the scroll is on the viewport, what you need to do is bind an action to the scroll event to check if the element is in the view each time the event is trigger. Pretty much like this:
$(window).scroll(function() {
check_element_position();
});
Now, in order for you to know if the element is in the viewport, you need 3 things. The offset top of that element, the size of the viewport and the scroll top of the window. Should pretty much look like this:
function check_element_position() {
var win = $(window);
var window_height = win.height();
var element = $(your_element);
var elem_offset_top = element.offset().top;
var elem_height = element.height();
var win_scroll = win.scrollTop();
var pseudo_offset = (elem_offset_top - win_scroll);
if (pseudo_offset < window_height && pseudo_offset >= 0) {
// element in view
}
else {
// elem not in view
}
}
Here, (elem_offset_top - win_scroll) represent the element position if there was no scroll. Like this, you just have to check if the element offset top is higher then the window viewport to see if it's in view or not.
Finally, you could be more precise on you calculations by adding the element height (variable already in there) because the code i just did will fire the event even if the element is visible by only 1 pixels.
Note: I just did that in five minutes so you might have to fix some of this, but this gives you a pretty darn good idea of what's going on ;)
Feel free to comment and ask questions